1. Field of the Invention
The present invention relates to a method for manufacturing a metal-semiconductor contact in a semiconductor component made of a semiconductor material and produced in a process, such as a transistor produced in a standard CMOS process, which to terminate the process is provided with a layer system having an arrangement of electrically insulating and electrically conductive layers (also called a BEOL layer below; BEOL: back end of line). Moreover, the invention relates to a semiconductor component, such as a transistor produced in a standard CMOS process, with at least one metal-semiconductor contact, manufactured according to a method of the invention, and in general an especially light-sensitive metal-semiconductor contact (photodiode).
2. Description of the Background Art
Semiconductor components with a metal-semiconductor contact, a so-called Schottky contact, which because of the disappearing charge storage in the on state represents an extremely fast switching (Schottky) diode, which brings about circuitry advantages known to the person skilled in the art, or methods for the manufacture thereof are known, for example, from the Unexamined German Patent Applications, DE 26 31 873 C2 (which corresponds to U.S. Pat. No. 4,173,063) and DE 29 21 971 C2 (which corresponds to U.S. Pat. No. 4,206,540), the European Patent EP 0 182 088 A1 (which corresponds to U.S. Pat. No. 4,859,616), U.S. Pat. No. 5,216,264, U.S. Pat. No. 6,656,823 B2, U.S. Pat. No. 6,784,035 B2, and from a publication by Soole and Schumacher from the year 1990 (IEEE Trans. Electron. Devices 37, 2285). Certain metal-semiconductor contacts, such as tungsten (Wo)-silicon, titanium (Ti)-silicon, or platinum (Pt)-silicon, possess in addition light-sensitive properties and thereby can also be used as photodiodes. In this regard, provided this is explicitly disclosed in the aforementioned publications, depending on the employed semiconductor material and its doping, the deposition of a metal is routinely necessary to produce the Schottky contacts. According to the prior art, this is associated with a considerable risk of contamination, because certain metals (Me), particularly Pt, diffuse extensively into the semiconductor material, e.g., silicon (Si), which has a negative effect on the lifetime of the charge carrier in the semiconductor. This can result in failure of the affected components and lead to production rejects with the associated negative consequential costs. For this reason, manufacturing plants for semiconductor components must be kept strictly free of Me+ ions. 
In practice, to circumvent the aforementioned difficulty in the manufacture of Schottky diodes or photodiodes and in general semiconductor components with metal-semiconductor contact(s), Ti, which binds well especially with silicon semiconductor material and exhibits hardly any diffusion effects, is used preferably as the metal. However, Pt-Si contacts in particular offer certain electrical advantages. Thus, Pt on n-Si has a high voltage barrier, so that only a very low dark current flows, which represents a great advantage for certain applications. Moreover, the Me silicides, which must be generated in the contact production for an intimate bond, in the case of Ti form only at temperatures T>600° C., which during annealing can lead to damage to the already produced semiconductor structures. In contrast, Pt or Wo suicides already form at T<300-400° C., which is why the possible use of these metals would bring about additional production advantages, but is not an option in practice in the course of manufacturing methods employed thus far.